Method and system for furnace sealing

ABSTRACT

The present invention relates generally to furnace systems and more particularly, but not by way of limitation, to a split-ring assembly for sealing a junction between a catalyst tube and a furnace. In one aspect, the present invention relates to a ring-seal assembly. The ring-seal assembly includes a housing ring coupled to an outer surface of a furnace. The housing ring is disposed around a circumference of a tube proximate a junction with the furnace. The ring seal assembly further includes a brush seal that is at least partially disposed within the housing ring. The brush seal is disposed around the circumference of the tube. A plurality of brushes extend radially inwardly from the brush seal towards the tube.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/540,266, filed on Nov. 13, 2014. U.S. patent application Ser. No.14/540,266 claims priority to U.S. Provisional Patent Application No.61/903,770, filed Nov. 13, 2013.

BACKGROUND

Field of the Invention

The present application relates generally to furnace systems and moreparticularly, but not by way of limitation, to a split-ring assembly forsealing a junction between a catalyst tube and a furnace.

History of the Related Art

Furnaces used in the refining and petro-chemical industries are designedto operate with interior temperatures in excess of 1600 degreesFahrenheit. Factors of economy and safety dictate the these interiortemperatures be controlled with a high degree of precision. It is thus,imperative that any penetration of ambient air into the interior of thefurnace and leakage of heat and hot flue gases from the furnace beminimized with a sealing device.

In many cases, the area near the top of the furnace is a primarylocation for leakage of flue gases and furnace heat. The area near thetop of the furnace is highly congested with numerous hardware including,for example, catalyst tubes, catalyst tube flanges, inlet piping,tube-support assemblies, and associated hardware. Such congestion limitsthe space available for installation of a sealing device. Becausefurnace components and associated hardware are often metallic, anysealing device must allow vertical growth, due to thermal expansion, of,for example, a catalyst tube. In addition, a sealing device mustfacilitate installation and replacement without altering or removing theassociated hardware.

SUMMARY

The present invention relates generally to furnace systems and moreparticularly, but not by way of limitation, to a split-ring assembly forsealing a junction between a catalyst tube and a furnace. In one aspect,the present invention relates to a ring-seal assembly. The ring-sealassembly includes a housing ring coupled to an outer surface of afurnace. The housing ring is disposed around a circumference of a tubeproximate a junction with the furnace. The ring seal assembly furtherincludes a brush seal that is at least partially disposed within thehousing ring. The brush seal is disposed around the circumference of thetube. A plurality of brushes extend radially inwardly from the brushseal towards the tube.

In another aspect, the present invention relates to a method of sealinga junction between a tube and a furnace. The method includes installinghousing ring to an outer surface of a furnace. The housing ring isinstalled about a circumference of a tube proximate a junction with thefurnace. The method further includes installing a brush seal around thecircumference of the tube. The brush seal is at least partially disposedwithin the housing ring. A plurality of brushes extending radiallyinwardly from the brush seal and contact an outer surface of the tube.The brush seal is seated within the housing ring.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention and forfurther objects and advantages thereof, reference may now be had to thefollowing description taken in conjunction with the accompanyingdrawings in which:

FIG. 1 is a perspective view of a prior-art catalyst tube arrangement;

FIG. 2 is an exploded view of a ring seal according to an exemplaryembodiment;

FIG. 3 is a perspective view of the ring seal of FIG. 2 in an installedconfiguration according to an exemplary embodiment;

FIG. 4A is a cross-sectional view of the ring seal of FIG. 2 in aninstalled configuration according to an exemplary embodiment;

FIG. 4B is a top view of the ring seal of FIG. 2 in an installedconfiguration according to an exemplary embodiment; and

FIG. 5 is a flow diagram of a process for sealing a catalyst tubeaccording to an exemplary embodiment.

DETAILED DESCRIPTION

Various embodiments of the present invention will now be described morefully with reference to the accompanying drawings. The invention may,however, be embodied in many different forms and should not be construedas limited to the embodiments set forth herein.

FIG. 1 is a perspective view of a prior-art catalyst tube arrangement. Afurnace 100 includes a plurality of catalyst tubes 102 extendingoutwardly therefrom. A fabric seal 104 is placed around each tube of theplurality of catalyst tubes near a junction with an outer wall of thefurnace 100. The fabric seal 104 is flexible and must be installed withsufficient slack to allow room for thermal expansion of the plurality ofcatalyst tubes 102 during operation. The excess material required toaccommodate thermal expansion is constrained by available space thusmaking installation and maintenance difficult.

FIG. 2 is an exploded view of a ring seal 200. The ring seal 200includes a brush seal 204 that is disposed between a housing ring 202and a retaining ring 206. The housing ring 202 includes a firstsplit-ring section 202(a) coupled to a second split-ring section 202(b).In other embodiments, however, ring seals utilizing principles of theinvention may include a single-piece housing ring or a hinged housingring. A rabbet 214 is formed around an interior circumference of thefirst split-ring section 202(a) and the second split-ring section202(b).

Still referring to FIG. 2, the brush seal 204 includes a firstbrush-seal ring 205, a second brush-seal ring 207, and a thirdbrush-seal ring 209 disposed within the housing ring 202. In otherembodiments, however, ring seals utilizing principles of the inventionmay include any number of brush-seal rings. The first brush-seal ring205 includes a first joint 216, the second brush-seal ring 207 includesa second joint 218, and the third brush-seal ring 209 includes a thirdjoint 220. When installed, the first brush-seal ring 205, the secondbrush-seal ring 207, and the third brush-seal ring 209 are arranged suchthat the first joint 216, the second joint 218, and the third joint 220are staggered such that the first joint 216, the second joint 218, andthe third joint 220 are not aligned thereby inhibiting transmission ofgases through the first joint 216, the second joint 218, and the thirdjoint 220.

Still referring to FIG. 2, the first brush-seal ring 205 includessupport ring 210(a) and a plurality of brushes 212(a) extending radiallyinwardly from the support ring 210(a). The second brush-seal ring 207includes support ring 210(b) and a plurality of brushes 212(b) extendingradially inwardly from the support ring 210(b). The third brush-sealring 209 includes support ring 210(c) and a plurality of brushes 212(c)extending radially inwardly from the support ring 210(c).

Still referring to FIG. 2, the retaining ring 206 is disposed above thebrush seal 204. The retaining ring 206 includes a first section 222 anda second section 224. In other embodiments, however, ring sealsutilizing principles of the invention may include a single-pieceretaining ring or a hinged retaining ring. The retaining ring 206 issecured to the housing ring 202 by a plurality of screws 208 therebysecuring the brush seal 204 between the housing ring 202 and theretaining ring 206.

FIG. 3 is a perspective view of the ring seal 200 in an installedconfiguration. The ring seal 200 is secured around a circumference of anouter wall 304 of a tube 302 at a junction between the tube 302 and afurnace arch or a furnace roof (not shown in FIG. 3). In a typicalembodiment, the tube 302 is, for example, a catalyst tube; however, inother embodiments, the ring seal 200 may be used to seal any type offurnace-inlet or furnace-outlet tube.

Referring to FIGS. 2-3, the first brush-seal ring 205, the secondbrush-seal ring 207, and the third brush-seal ring 209 are securedwithin the housing ring 202. The brushes 212(a)-(c) extend radiallyinwardly from the support rings 210(a)-(c) and contact the outer wall304 of the tube 302 thereby inhibiting the transmission of gases betweenthe outer wall 304 and the ring seal 200. The tube 302, however, is notconnected to the brushes 212(a)-(c). Thus, the tube 302 may move, forexample, in an axial direction relative to the ring seal 200. Suchmovement of the tube 302 may be, for example, due to thermal expansionand/or thermal contraction of the tube 302.

FIG. 4A is a cross-sectional view of the ring seal of 200 in aninstalled configuration. FIG. 4B is a top view of the ring seal 200 inan installed configuration. Referring to FIGS. 4A and 4B, the firstsplit-ring section 202(a) is coupled to the second split-ring section202(b) to form the housing ring 202 around the outer wall 304 of thetube 302. Use of the first split-ring section 202(a) and the secondsplit-ring section 202(b) allows the ring seal 200 to be utilized withexisting furnaces without need for significant equipment removal. Thehousing ring 202 is secured to an outer wall 402 of a furnace 404 via aprocess such as, for example, welding, brazing, or the like.

Still referring to FIGS. 4A and 4B, the first brush-seal ring 205, thesecond brush-seal ring 207, and the third brush-seal ring 209 aredisposed within the housing ring 202 above the rabbet 214. The brushes212(a)-(c) extend radially inwardly from the support rings 210(a)-(c)and contact the outer wall 304 of the tube 302 thereby inhibiting thetransmission of gases between the outer wall 304 of the tube 302 and thering seal 200. The tube 302, however, is not connected to the brushes212(a)-(c). Thus, the tube 302 may move, for example, in an axialdirection relative to the ring seal 200. Such movement of the tube 302may be, for example, due to thermal expansion and/or thermal contractionof the tube 302. The retaining ring 206 is positioned above the firstbrush-seal ring 205, the second brush-seal ring 207, and the thirdbrush-seal ring 209. The retaining ring is secured to the housing ring202 by the plurality of screws 208.

FIG. 5 is a flow diagram of a process 500 for sealing a catalyst tube.The process 500 starts at step 502. At step 504, the first split-ringsection 202(a) and the second split-ring section 202(b) are assembledaround a base region of the tube 302. The first split-ring section202(a) and the second split-ring section 202(b) are coupled together toform the housing ring 202 via the screws 406. Use of the firstsplit-ring section 202(a) and the second split-ring section 202(b) allowthe housing ring 202 to be installed without removal or alteration ofthe tube 302 or the furnace 404. At step 506, the first brush-seal ring205, the second brush-seal ring 207, and the third brush-seal ring 209are wound around the outer wall 304 of the tube 302 to form the brushseal 204. The first joint 216, the second joint 218, and the third joint220 are arranged in a staggered configuration such that the first joint216, the second joint 218, and the third joint 220 are not aligned. Sucha configuration improves the sealing properties of the brush seal 204 byinhibiting transmission of gas through the first joint 216, the secondjoint 218, and the third joint 220. At step 508, the brush seal 204 isdisposed within the housing ring 202 and seated on the rabbet 214. Atstep 510, the first section 222 and the second section 224 are securedaround the tube 302. The first section 222 and the second section 224are coupled to each other to form the retaining ring 206. At step 512,the retaining ring 206 is secured to the housing ring 202 via theplurality of screws 208. The process 500 ends at step 514.

Referring now to FIGS. 2-5, during operation, the brush seal 204 createsa sufficient barrier so as to inhibit infiltration of ambient air intothe furnace 404 as well as to inhibit escape of flue gas from thefurnace 404. The plurality of brushes 212(a)-(c) contain many bristlesthat create a tortuous flow path for escape of internal heat and fluegases from the furnace 404. Further, use of the first brush-seal ring205, the second brush-seal ring 207, and the third brush-seal ring 209creates multiple air layers around the perimeter of the tube 302. Themultiple air layers isolate internal heat and flue gases within thefurnace 404 and, thus, provide effective sealing. The ring seal 200permits axial movement of the tube 302 therethrough. Thus, axialexpansion and contraction of the tube 302 due to, for example, thermalexpansion, is facilitated. In addition, use of the housing ring 202 andthe retaining ring 206 allows the ring seal 202 to be installed,maintained, and replaced without removal or alteration of the furnace404 or the tube 302.

Although various embodiments of the method and system of the presentinvention have been illustrated in the accompanying Drawings anddescribed in the foregoing Specification, it will be understood that theinvention is not limited to the embodiments disclosed, but is capable ofnumerous rearrangements, modifications, and substitutions withoutdeparting from the spirit and scope of the invention as set forthherein. It is intended that the Specification and examples be consideredas illustrative only.

What is claimed is:
 1. A ring-seal assembly comprising: a housing ringcoupled to an outer surface of a furnace and disposed around acircumference of a catalyst tube proximate a junction with the furnace,the housing ring comprising a first semi-circular ring half coupled to asecond, oppositely-disposed, semi-circular ring half; a plurality ofsplit brush-seal rings at least partially disposed within the housingring, the plurality of split brush-seal rings disposed around thecircumference of the catalyst tube, each brush-seal ring of theplurality of split brush-seal rings comprising a single joint, wherein ajoint of a first split brush-seal ring of the plurality of splitbrush-seal rings is arranged in a circumferentially staggeredorientation from a joint of an adjacent split brush-seal ring of theplurality of split brush-seal rings; the plurality of split brush-sealrings comprising a plurality of brushes extending radially inwardlytowards the catalyst tube; and wherein, the ring-seal assembly isinstalled from a side of the catalyst tube and without removal of thecatalyst tube.
 2. The ring-seal assembly of claim 1, comprising aretaining ring coupled to the housing ring, the retaining ring splitinto two semi-circular halves.
 3. The ring-seal assembly of claim 1,wherein the plurality of split brush-seal rings permits axial expansionof the catalyst tube due to thermal expansion.
 4. The ring-seal assemblyof claim 1, wherein the plurality of brushes contact an outer surface ofthe catalyst tube.
 5. The ring-seal assembly of claim 1, wherein theplurality of brushes inhibits transmission of gases from the furnace. 6.The ring-seal assembly of claim 1, wherein the plurality of splitbrush-seal rings are seated within a rabbet formed in the housing ring.7. A method of sealing a junction between a tube and a furnace, themethod comprising: installing a housing ring to an outer surface of afurnace and about a circumference of a catalyst tube proximate ajunction with the furnace, the housing ring comprising a firstsemi-circular ring half coupled to a second oppositely-disposedsemi-circular ring half; installing a plurality of split brush-sealrings around the circumference of the catalyst tube and at leastpartially disposing the plurality of split brush seal rings within thehousing ring, each brush seal ring of the plurality of split brush-sealrings comprising a single joint; arranging the plurality of splitbrush-seal rings such that a joint of a first split brush-seal ring ofthe plurality of split brush-seal rings is circumferentially staggeredfrom a joint of an adjacent split brush-seal ring of the plurality ofsplit brush-seal rings; contacting a plurality of brushes extendingradially inwardly from the plurality of split brush-seal rings with anouter surface of the catalyst tube; and seating the plurality of splitbrush-seal rings within the housing ring.
 8. The method of claim 7,comprising: coupling a retaining ring to the housing ring, the retainingring being split into two semi-circular halves.
 9. The method of claim7, wherein the installing the plurality of split brush-seal ringscomprises wrapping the plurality of split brush-seal rings around thecatalyst tube such that the plurality of split brush-seal rings may beinstalled and removed without removal of the catalyst tube.
 10. Themethod of claim 7, wherein contact pressure between the brushes and theouter surface of the catalyst tube inhibits transmission of gases fromthe furnace.
 11. The method of claim 7, wherein the seating theplurality of split brush-seal rings within the housing ring comprisesdisposing the plurality of split brush-seal rings within a rabbet formedin the housing ring.